/*
 *    Copyright 2009-2022 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       https://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package copy.org.apache.ibatis.parsing;

/**
 * @author Clinton Begin
 */
public class GenericTokenParser {

 private final String openToken;
 private final String closeToken;
 private final TokenHandler handler;

 public GenericTokenParser(String openToken, String closeToken, TokenHandler handler) {
  this.openToken = openToken;
  this.closeToken = closeToken;
  this.handler = handler;
 }

 public String parse(String text) {
  if (text == null || text.isEmpty()) {
   return "";
  }
  // search open token
  int start = text.indexOf(openToken);
  if (start == -1) {
   return text;
  }
  char[] src = text.toCharArray();
  int offset = 0;
  final StringBuilder builder = new StringBuilder();
  StringBuilder expression = null;
  do {
   if (start > 0 && src[start - 1] == '\\') {
    // this open token is escaped. remove the backslash and continue.
    builder.append(src, offset, start - offset - 1).append(openToken);
    offset = start + openToken.length();
   } else {
    // found open token. let's search close token.
    if (expression == null) {
     expression = new StringBuilder();
    } else {
     expression.setLength(0);
    }
    builder.append(src, offset, start - offset);
    offset = start + openToken.length();
    int end = text.indexOf(closeToken, offset);
    while (end > -1) {
     if (end > offset && src[end - 1] == '\\') {
      // this close token is escaped. remove the backslash and continue.
      expression.append(src, offset, end - offset - 1).append(closeToken);
      offset = end + closeToken.length();
      end = text.indexOf(closeToken, offset);
     } else {
      expression.append(src, offset, end - offset);
      break;
     }
    }
    if (end == -1) {
     // close token was not found.
     builder.append(src, start, src.length - start);
     offset = src.length;
    } else {
     builder.append(handler.handleToken(expression.toString()));
     offset = end + closeToken.length();
    }
   }
   start = text.indexOf(openToken, offset);
  } while (start > -1);
  if (offset < src.length) {
   builder.append(src, offset, src.length - offset);
  }
  return builder.toString();
 }
}
